| Present "doubt" | I | doubt | |
| Present Continuous "doubt" | I | am doubting | |
| Simple past "doubt" | I | doubted | |
| Past Continuous "doubt" | I | was doubting | |
| Present perfect "doubt" | I | have doubted | |
| Present perfect continuous "doubt" | I | have been doubting | |
| Past perfect "doubt" | I | had doubted | |
| Past perfect continuous "doubt" | I | had been doubting | |
| Future "doubt" | I | will doubt | |
| Future continuous "doubt" | I | will be doubting | |
| Future perfect "doubt" | I | will have doubted | |
| Future perfect continuous "doubt" | I | will have been doubting |